Players can find loot (such as clothing, weapons, and armor) throughout the game world and collect it. Players can trade items for currency and better equipment. Trade takes place while interacting with certain friendly non-player characters, such as shopkeepers, and often uses a specialized trading screen. Purchased items go into the player’s inventory. Some games turn inventory management into a logistical challenge by limiting the size of the player’s inventory, thus forcing the player to decide what they must carry at the time. This can be done by limiting the maximum weight that a player can carry, by employing a system of arranging items in a virtual space, or by simply limiting the number of items that can be held.